1. Field of the Invention
The present invention relates to a liquid volume detector for detecting the volume of a liquid in a container capable of containing the liquid, a liquid mixture supply system adopting such a liquid volume detector and an image forming apparatus.
2. Description of the Related Art
An image forming apparatus is provided with an image forming assembly for forming an image on a sheet based on image information, a fixing device for fixing the image formed in the image forming assembly to the sheet, and a discharging device for discharging the sheet having the image fixed thereto in the fixing device. In this image forming apparatus, the image is formed on the sheet in the image forming assembly and fixed in the fixing device. The sheet having the image fixed thereto is discharged from the discharging device.
In some of image forming apparatuses using liquid developers, residual developers, which were not used for development at the time of image development, are collected for reutilization. In an image forming apparatus of such a type, a residual developer is collected into a container containing the developer and supplied to a developing device provided in the image forming assembly to be reused after agitation and density adjustment.
In such an image forming apparatus, the developer is supplied to the container if the volume of the developer in the container decreases. The supply of the developer is stopped if a liquid volume detector detects that the volume of the developer in the container has reached a specified level (see Japanese Unexamined Patent Publication No. S59-126570).
In the liquid volume detector disclosed in this patent literature, a float is accommodated in the container and moves up and down in the container according to the volume of the developer and the liquid volume is detected depending on the position of the float. The supply of the residual developer is stopped when the float moves to an uppermost position. However, if the viscosity of the developer is high, there are cases where the position of the float does not move up even if the volume of the developer increases. Thus, it is difficult to accurately regulate the volume of the developer in the container due to, for example, the excessive supply of the developer into the container.